Abstarct: Intelligent transport systems have been presented as an inevitable solution traffic problems and loss of time, money and lives, the ability to identify the offending car and law enforcement surveillance on that case, is vital. enhancing illumation and ambiguity elimination is One of the for cases that the license plate image recognition algorithms is considered. weakly illumination images, is causing problems in image processing. Thus far, techniques and different algorithms are used to enhancing illumination. In this thesis, a pre-processing to correct low light image of plate is presented. Retinex method for correcting the brightness for the first time on the Persian plates were used and acceptable results have been achieved. The output of this pre-processing application have been given to plate recognition application of Golbafan group and have been improved the results. the probability of false detection of license plate in the Farsi Golbafan group system decreased from the 85% to 11.25%.